This invention relates generally to data storage devices, and more particularly to an arbitration mechanism for logical quorums resources within a storage network.
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to the software and data as described below and in the drawing hereto: Copyright (copyright) 1999, Microsoft Corporation, All Rights Reserved.
As computer systems have evolved so has the availability and configuration of data storage devices, such as magnetic or optical disks. For example, these storage devices can be connected to the computer system via a bus, or they can be connected to the computer system via a wired or wireless network. In addition, the storage devices can be separate or co-located in a single cabinet.
A storage network is a collection of interconnected computing systems, referred to as nodes, operating as a single storage resource. A storage network allows a system to continue to operate during hardware or software failures, increases scalability by allowing nodes to be easily added and simplifies management by allowing an administrator to manage the nodes as a single system.
Cluster software exists on each node and manages all cluster-specific activity of a storage network. The cluster software often executes automatically upon startup of the node. At this time the cluster software configures and mounts local, non-shared devices. The cluster software also uses a xe2x80x98discoveryxe2x80x99 process to determine whether other members of the storage network are operational. When the cluster software discovers an existing cluster, it attempts to join the cluster by performing an authentication sequence. A cluster master of the existing cluster authenticates the newcomer and returns a status of success if the joining node is authenticated. If the node is not recognized as a member then the request to join is refused.
If a cluster is not found during the discovery process, the node will attempt to form its own cluster. This process is repeated any time a node cannot communicate with the cluster to which it belongs. In conventional computing systems, nodes arbitrate for a physical xe2x80x9cquorum resourcexe2x80x9d, such as a disk, in order to form a storage network. In more recent systems, a quorum resource can be a logical resource, such as a volume, that includes one or more physical quorum resources. For example, a volume is a logical storage unit that can be a fraction of a disk, a whole disk, fractions of multiple disks or even multiple disks.
In conventional systems the responsibility and intelligence for determining ownership of a cluster, i.e. the implementing the arbitration process, is often distributed between several components and/or software modules. The responsibility for configuring and managing the underlying storage devices is often is often similarly distributed. This lack of clean division in responsibility creates difficulties when a given component or software module changes. Thus, there is a need in the art for a system that more cleanly separates the responsibilities of cluster arbitration from the cluster management from the responsibility of volume management and the underlying storage devices.
The above-mentioned shortcomings, disadvantages and problems are addressed by the present invention. Inventive cluster management software and volume management software execute on the nodes of a storage network and operate in cooperation with the underlying operating system in order to arbitrate for logical quorum resources such as a quorum volume. According to the invention, the cluster management software arbitrates for logical quorum resources and forms a storage network without having knowledge of the underlying physical quorum resources. In this fashion, the cluster management software is not hardware specific. In addition, the cluster management software need not be aware of how the logical quorum resource is formed from the underlying physical quorum resources. For example, the volume management software manages is solely responsible for forming and mounting the logical quorum volume. The volume management software performs volume management without having detailed knowledge of the arbitration process and the determination of ownership.